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A bit of background first. My Marshall JMP 50 watter was working well and sounding great, except for one problem. The turret board had become conductive. So far the only sympton of this is that the pots on the amp sound scratchy as their mechanical movement is being amplified through the speakers, and secondly that the pot movement on my guitars is also being amplified through the speakers, and any switch movements result in a popping noise coming through the amp. Besides that, it hardly hums and is generally very quiet.

Over the last couple of months I've been trying to decide what to do about this, and about 2 weeks ago I decided to jump in with both feet. Unfortunately for those of you who accidentally clicked this link, you will have to suffer through watching me, Electronica Ignoramus, attempting something which for me, I believe is fairly ambitious. Firstly, Im going to replace the turret board, and secondly my OCD is going to try to assist me in neatening up all the wiring, which was irritating me. Oh, I'm also going to, as far as possible, do all the work myself, and only involve a tech if I get stuck or have a problem.

Here are some Before pics:









    Gutted:



    Power source for heaters rerouted and reattached:



    Installation of new heater wiring in progress:



    Heater wiring completed:


      New phenolic turret board. This board is a very good match for the stuff Marshall was using in the early days:



      Add some turrets:



      Equals staked board:



      Board test fitted to chassis:



      I've added an extra turret to this board in case I decide to convert to the 1987 Lead circuit instead of staying as a 1986 Bass circuit.

      That's it for now. Waiting for some more parts to arrive over the next couple of days. Stay tuned.

        That's pretty awesome. I think OCD is a good thing when building/rebuilding amps like this. ?
          Cool! Don't worry, tis easily doable especially if you have a touch of OCD on your side :yup:.

          A thing to remember, absolute implicit neatness is not always the way. For example, AFAICS your heater wiring could be more efficient. I don't know what your knowledge is like regarding layout and lead dress, but if you haven't, I would suggest you read up on it a bit.

          http://www.geofex.com/article_folders/lead_dress/lead_dress_in_tube_amps.htm

          http://valvewizard2.webs.com/Grounding.pdf

          Good luck ?
            It's actually CDO.
            (it needs to be alphabetically sorted !!)
              Thanks for the links, makepeace. Very interesting reading.

              Re the heater wires, I agree that particularly the black leads could be slightly shorter. Strangely in this new layout both the red and black leads are already over an inch shorter than the leads they replaced. Re their layout, I'm copying what I have seen in photos of other similar amps as well as the recommended layout of the Metro Amp kits.
                The first of 3 sets of NOS Mullard mustard caps arrived today:


                  Local or import? ? Coool!
                    This set was an import and I've got another identical set on the way that were also imports. I've then also got a set of 5 x 0,1uf that are marked Philips Miniwatt that I found locally.
                      Tough crowd...

                      Anyway, here's the board wired in and nearly done being populated:
                        Hey, you've basically built your own amp ? Looks REAL good, well done
                          Looks amazing.
                          I've been thinking that you can probably tell a whole lot about someone's personality based on what their wiring looks like.
                          Mine would not look like that, no matter how hard I tried.
                            That's looking really good.

                            It's going to be something to be proud of!
                              Cool, well done! ?

                              How about for R50 bucks you re-wire mine too (and throw in your transformer for good measure ? )

                              but only for today!!
                                I also like the funky purple wires.